Attempts have been made to decorate surfaces of three-dimensional components used in exterior and interior components of automobiles and motorcycles, electronic components, furniture, and so on or the surface of articles such as three-dimensional substrates having a complex shape, such as shapes that include protrusions and recesses on the surface, by laminating with a colored (e.g., paint replacement) or designed plastic film instead of using conventional decorations (e.g., liquid paint).
As methods for laminating a film on the surface of this type of article, film lamination forming methods using vacuum forming apparatuses are known. Japanese Unexamined Patent Application Publication No. 2002-67137 describes the constitution of a vacuum forming apparatus and the procedure for a method of laminating a plastic sheet on a core material using this vacuum forming apparatus. As disclosed in the Japanese Unexamined Patent Application Publication No. 2002-67137, vacuum forming apparatuses generally have an upper chamber and a lower chamber able to be joined to and separated from each other, with a heater incorporated into the upper chamber.
In a common lamination method using a vacuum forming apparatus, an article on which a film is to be laminated is supported in the lower chamber and a plastic film that is the formed object is disposed between the upper chamber and the lower chamber. Next, the upper chamber is lowered so that the upper and lower chambers each form an enclosed region with the plastic film, and the conditions inside the upper chamber and the lower chamber are changed from atmospheric pressure to a vacuum state by means of a vacuum pump. Thereafter, the plastic film is softened by being heated by the heater in the upper chamber and air is introduced into the upper chamber only. By creating a pressure difference between the upper chamber and the lower chamber in this way, the plastic film is laminated on the surface of the article in the lower chamber.